In autumn 1379, the power of the British crown is invested in John of Gaunt, and the kingdom is seething with discontent. The French are attacking the southern ports and peasants are planning a revolt organized by a mysterious leader who proclaims himself “IRA DEI,” the anger of God. Meanwhile Gaunt's tenuous plans are plunged into chaos by a series of bloody murders in London. In desperation, Gaunt turns to Sir John Cranston to catch the killer and recover a vanished king’s ransom in gold. Together with his ally Brother Athelstan, Cranston must face threats from the most powerful classes as well as attacks from the seedy underworld—along with a chilling exorcism—in order to bring a subtle murderer to justice.